Earth is warmed by heat-trapping gases, also called greenhouse gases, that are present in the atmosphere. Greenhouse gases have kept the temperature of the planet in a range hospitable for life as we know it for a long time. Recently, due to human activity, levels of greenhouse gases, such as carbon dioxide, have been increasing in the atmosphere. This increase threatens to make Earth warmer than it has been for millions of years. As a result of this planetary warming trend, sea level will also rise.
Throughout the world, temperatures are higher on land, in the air, at the sea surface, underground, and under ice. Ice covered areas are receding, and recent data suggests that the polar ice caps may be melting faster than expected. There is also evidence that tropical storms may be growing more intense. In New Jersey, long-term data document a significant increase in average temperature, and a significant rise in sea level that is consistent with observed and predicted global trends.
Rising ambient temperatures are expected to have direct and indirect impacts on human health and the environment in New Jersey. Direct human health impacts are likely to include increased heat stress, especially for vulnerable urban populations, such as the elderly and urban poor. Climate models predict an increase in the number of days per year with temperatures above 90o F in the New York City metro area, with a potentially significant impact on human health due to heat stress.
Natural ecosystems, water supply and agriculture are also likely to be affected by warmer temperatures and associated changes in the water cycle. Climate-related habitat loss could lead to extinction of some threatened species. Warmer temperatures are expected to lead to more intense rain events, since warm air holds more water vapor. However, warmer temperatures also are likely to lead to greater evaporation and transpiration of moisture, which could cause drier conditions in soils.
Recent modeling work predicts that temperatures in the Northeast U.S. are likely to rise 2.5 to 4 degrees F in the winter and 1 to 3 degrees F in the summer over the next several decades. These changes will result from GHG emissions that have already occurred, because it will take the climate many years to respond to changes in levels of GHGs in the atmosphere that have already been reached. However, over the longer term, further changes to the climate depend strongly on emissions choices made now and through the end of the century.
Without significant long-term reductions in GHG emissions, the model predicts that the Northeast can expect many more extremely hot days and more events of extreme rainfall, especially in winter. Although there is likely to be more precipitation overall, the likelihood of summer droughts will increase, because the higher temperatures will dry soils faster; one- to three-month droughts could happen almost every year by the end of the century.
However, the model predicts that if measures are instituted that allow the world to follow a path of economic growth based on less fossil fuel-intensive industry and more use of renewable energy that would cause GHG emissions to peak around mid-century and then decline, many of the projected changes in the Northeast will be much less severe, e.g. the likelihood of short-term droughts will be only slightly higher than today.
Sea level rise due to climate change is of major concern to New Jersey. New Jersey is especially vulnerable to significant impacts due to geologic subsidence, the topography of its coastline, current coastal erosion, and a high density of coastal development.
A sea level rise in line with median projections would threaten the majority of New Jersey’s coastline. The effects of sea level rise will be exacerbated in New Jersey since relative sea level rise in New Jersey will be greater than the global average due to coastline subsidence. Recent measurements suggest that the rate of melting of the Greenland ice sheet has increased dramatically. If an increased rate of melting is substantiated by further data, and if the melting continues at this rate or accelerates further, the rate of sea level rise throughout the world will increase significantly. Effects of rising sea level are magnified during storm events. Higher sea levels will increase the severity of storm-related flooding in coastal and bay areas. In addition to significant property losses, sea level rise will adversely impact coastal ecosystems and may threaten coastal fresh water supplies due to salt-water intrusion.
Currently, responses to rising sea levels and increasing erosion along the NJ coast have been the construction of sea walls and bulkheads, raising land elevation with beach nourishment projects, and the building of jetties to capture sand. All of these approaches are expensive, and the costs can be expected to increase as sea level rises further. The additional impact of anticipated more intense storms and floods when coupled with higher sea levels will likely compound the growth in costs.